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| 1 | A molecular dynamics study of laser-excited gold显示文摘The structural evolution of laser-excited systems of gold has previously been measured through ultrafast MeV electron diffraction.However,there has been a long-standing inability of atomistic simulations to provide a consistent picture of the melting process,leading to large discrepancies between the predicted threshold energy density for complete melting,as well as the transition between heterogeneous and homogeneous melting.We make use of two-temperature classical molecular dynamics simulations utilizing three highly successful interatomic potentials and reproduce electron diffraction data presented by Mo et al.[Science 360,1451–1455(2018)].We recreate the experimental electron diffraction data,employing both a constant and temperature-dependent electron–ion equilibration rate.In all cases,we are able to match time-resolved electron diffraction data,and find consistency between atomistic simulations and experiments,only by allowing laser energy to be transported away from the interaction region.This additional energy-loss pathway,which scales strongly with laser fluence,we attribute to hot electrons leaving the target on a timescale commensurate with melting。 | Jacob M.Molina T.G.White | 2022 | Matter and Radiation at Extremes2022，7，3： | 1 |
| 2 | Implementation of a Faraday rotation diagnostic at the OMEGA laser facility显示文摘Magnetic field measurements in turbulent plasmas are often difficult to perform. Here we show that for kG magnetic fields, a time-resolved Faraday rotation measurement can be made at the OMEGA laser facility. This diagnostic has been implemented using the Thomson scattering probe beam and the resultant path-integrated magnetic field has been compared with that of proton radiography. Accurate measurement of magnetic fields is essential for satisfying the scientific goals of many current laser–plasma experiments. | A.Rigby J.Katz A.F.A.Bott T.G.White P.Tzeferacos D.Q.Lamb D.H.Froula G.Gregori | 2018 | High Power Laser Science and Engineering2018，6，3： | 0 |
| 3 | Insensitivity of a turbulent laser-plasma dynamo to initial conditions显示文摘It has recently been demonstrated experimentally that a turbulent plasma created by the collision of two inhomogeneous,asymmetric,weakly magnetized,laser-produced plasma jets can generate strong stochastic magnetic fields via the small-scale turbulent dynamo mechanism,provided the magnetic Reynolds number of the plasma is sufficiently large.In this paper,we compare such a plasma with one arising from two pre-magnetized plasma jets whose creation is identical save for the addition of a strong external magnetic field imposed by a pulsed magnetic field generator.We investigate the differences between the two turbulent systems using a Thomson-scattering diagnostic,x-ray selfemission imaging,and proton radiography.The Thomson-scattering spectra and x-ray images suggest that the external magnetic field has a limited effect on the plasma dynamics in the experiment.Although the external magnetic field induces collimation of the flows in the colliding plasma jets and although the initial strengths of the magnetic fields arising from the interaction between the colliding jets are significantly larger as a result of the external field,the energies and morphologies of the stochastic magnetic fields post-amplification are indistinguishable.We conclude that,for turbulent laser-plasmas with supercritical magnetic Reynolds numbers,the dynamo-amplified magnetic fields are determined by the turbulent dynamics rather than the seed fields or modest changes in the initial flow dynamics of the plasma,a finding consistent with theoretical expectations and simulations of turbulent dynamos. | A.F.A.Bott L.Chen P.Tzeferacos C.A.J.Palmer A.R.Bell R.Bingham A.Birkel D.H.Froula J.Katz M.W.Kunz C.-K.Li H-S.Park R.Petrasso J.S.Ross B.Reville D.Ryu F.H.Séguin T.G.White A.A.Schekochihin D.Q.Lamb G.Gregori | 2022 | Matter and Radiation at Extremes2022，7，4： | 0 |
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